Radioreceiver



I y 12, 1932- w. F. HOISING'TON 1,867,153

RADIORECEIVER- Filed Nov, 25, 1927 l l l l l l l l l l lll l lll fll l l i Patented July 12, 1932 warren stares,

' WILLIAM FOLWELL HOISIN GTON,

or PARIS, FRANCE, nssreivon 'ro cownn H. nuns, on Lennon, ENGLAND RADIORECEIVER Application filed November 25, 1827, Serial No. 235,525, and in Great Britain December 1, 1926. g i

r This invention relates to radio receivers and has particular application to those of the portable type. v

The principal object of'thetinvention' is to increase the volume, selectivity and quality of radio receivers, and to increase the range of frequencies over which radio receivers may be efiiciently operated.

thereof being tuned. The inductance of the 7 two windings is approximately equal and the inductance of each is approximately equal to that of the loop antenna or' the secondary associated with the antenna circuit.

More than one stage of high frequency amplification may of course be employed, the last stage being coupled to the detector as described. I

In accordance with another feature of the invention the radio receiver is provided with a radio wave interceptor made in two sections, one being of less number of turns than the other and the two sections being separated by several inches on a frame or other support. The smaller section has an inductance approximately one third that of the larger section. Each section is tapped, and is so associated with cooperating switching means that when only the smaller section or a por-' tion thereof is used for reception thelarger section is short-circuited.

The wave interceptor embodying this invention has a wave length range, the maXi-. mum of which is about ten timesthat of the minimum and there is no appreciable loss due to dead end or harmonic resonance.

The accompanying drawing illustrates a portable radio receiver embodying the features of the invention. I

Referring to the drawing, the radio receiver comprises a radio wave interceptor which takes the form of a loop antenna made up of two sections 1 and 2, a high frequency amplifier 3, a detector 4:, two lowfrequency amplifiers 5 and 6 and a loud speaker 7.

The loop antenna suitable for receiving over a wave length range from 200 to 2000 meters will be more particularly described. The upper section 1 consists of 26 turns of No. 22 S. VV. G. enamelled double cotton covered copper wire tapped at the twelfth turn from the filament end, with'the turns spaced a distance equivalent to the diameter of the wire. l The lower section 2, which is spaced approximately two inches from the upper section, consists of 69 turns of the same wire wound with the adjacent turns close together. 'The loop antennais controlled by a switch 8 and-is tuned to the wave length to be received by "a variable con-.

denser 9 of the square law type having a maximum capacity of .0003 microfarad.

- The upper portion of section 1 of this particular loop antenna is suitable for receiving waves of from approximately 200 to 400 metres, and the whole of section 1 is suitable for receiving waves of from approximately 350 to 5 50 metres. When section 1 only or a portion thereof is utilized, the Whole of section 2 is short-circuited to avoid interfer ence therefrom upon section I due to the c natural frequency of section 2, and the damping effect upon section 1 from the short-cir cuited section 2 is avoided by the proper spacing of the two sections. For the reception of waves of from approximately 850 to 1500 metres, all of, section 1 is connected in series with the upper portion of section 2. The entire two sections 1' and 2 connected in series are employed for receiving waves of from approximately 1400 to 2000 metres. To make the loop antenna suitable forjreceiving different ranges of wave lengths, the

sections thereof and their tappings can, of f course, be appropriately chosen. M This will be evident from considering the various circuits that maybe established by switch 8. The arm ofswitch 8 carries two permanent contacts 31 and 32. Contact 31 is connected to the filament of tube 3 and to the condenser 9. Contact 32 is connected ones. engaging theextreme left and. right 7 termlnals ofztheleftihand winding and right V neighbouring pair of contacts the former cir right pair of contacts.

whole ofsections'l and. 2.arein parallel with Y to the end of the upper portion of section 2 of the antenna. 'VVhen the arm of switch 8 is moved on to the first pair of contacts, whichare shown on the extreme left of the switch, the following connections are made grid, oftube 3, upper. portion of winding. 1,v contact 31 of switch- 8, filament of tube 3. Section 2 of the antenna is shortcircuited over contact 32. When the arm of switch 8 ismoved to occupy the second or:

9. and. filament of. tube 3. The fourth or last position of'sw-itch 8 is ,on' the. extreme In this; positionthe condenser 9.. The; circuit is". from condenser 9 over. section 1 tov contact 32.0f switch 8, over-section 2 to contact. 31. of. switch Sand 7 to. condenser '9.

The; opposite plates of'variable; condenser 9. are connected: tothe filament and grid repectively'of the-high. frequency amplifier 3.

'The'output: circuit of. amplifier 3 may. be

v coupled totheinput circuit of. detector4 byeitherof twoitransformers12-or 13 controlled-by a: double-throw four-pole switch 14... There are two activepositions for switch 14. I-n-.one position its. contact. arms allextend. upwardly toiengage-the' terminalsof the left and right. windings ofl transformer 12 as.-will be-obvious-rfrom the drawing. In the. other acti've position of. switch 8, the contact arms. extend downwardly the outer.

hand winding'of. transformer 13. The in ner. contact. arms, in. this position. of the switch, engage. blank. contacts Trans former-12 is employed when antennasection I or. only a. portion. thereof is? utilizedfor reception. Transformer. 13- is employed ,whe both antenna. sections. or section 1. and

the upper portion. only offsection 2. are. con.- nect'edr in circuit for reception.

When transformer 12' is connected in circuit, bothwindi'ngs. of" transformer 13 are short-circuited to avoid. interefernce there-.

from upon transformer 12 due to the natural f'requencyof transformer 13.. The-damping effect upon transformer 12' from. the shortcircuit'edf windings of. transformer 13 is avoided. by proper spacing, of the two. transformers which-are mounted at right angles The primary and secondary windings of each transformer employed in a radio receiver used for several months consist of honeycomb wound air core coils,.tl1e two coils of a trans former being mounted side by side and being relatively adjustable for a purpose heretofore alluded to and more particularly hereinafter described.

In the practical radio receiver referred to, the honeycomb Wound-coilsemployed had an inside diameter of 2 inches, the wire being of No. 26 S. W. G. single cottoncovered copper. Each coil of transformer 12 had 7 5 turns and H each coil of. transformer 13. had 300-turns.

W'hen either transformer is connected in circuit variable condenser 15 is-connected in,

closed circuit relation to thesecondary windlng of the connected transformer. and 1s em-' ployed to tune such secondary to the wave 7 length to'be received. This condenser 15 may be of the square lawtype and have a maximum capacity of .0003 microfarad.

The tuned secondary of high frequency transformerlZ or 13 is connected through condenser 16 to the grid of detector 4, while the usualleak'resistance 17, forcondenser 16 is connected across the grid and the filament ofdetector 4.

The output circuit of detector 4 is coupled to the input circuit of low frequency amplifier 5. by a transformer 18, the primary winding ofwhichis shunted. by aby-pass condenser 19 .forthe high frequency components ofthe detectedsignal modulatedwave. A transformer 21 couples the output cir cuit ofuamplifier 5 to. the input circuit of amplifier. 6. V

The'output circuit ofamplifier 6 has. con: nectedtherein loud speaker 7 shunted by condenser 23. f

Platecurrent. for they variousamplifiers and the detector is supplied from a high tension battery '25.

Grid biasingpotential for the gridsofthe low frequency amplifiers. is supplied from.

battery 27;

Current for heating the filaments of the 7 several amplifiers and the detector is supplied from battery 28, the circuit of which contains aswitch 29.

The high frequency apparatus shown Within the dotted rectangle 30 is shielded from the antennasections 1 and 2 and from the low frequency apparatus of the radio receiver to prevent detrimental reaction.

When tuning the illustrated radio receiver' for a new station having a wave lengthbetween 200 and 400metres, antenna switch 8 is set to its first position (left), switch 14 set to connect transformer 12in circuit and switch 29 is closed. Condenser 9 is then adjusted to find thestation and condenser 15 is adjus'ted to tune the high frequency transformer, secondary to approximately the wave I length .ofthe station,.after whichthecoupling be that the adjustable coupling permits a very fine adjustment of the damping upon the transformer secondary circuit thereby making it possible to obtain much sharper tuning therein which increases not only the strength of the signal but also the quality thereof. Sharper tuning of the transformer secondary allows the high frequency amplifier and the detector to operate most efiiciently' at any frequency. It follows that the selectivity of the radio receiver is also very greatlyincreased. It has been demonstrated that by making the windings of the high frequency trans former relatively adjustable to vary the coupline between the primary and secondary windings, as much as a 50 per cent increase of signal strength is obtained and the quality of the signal is improved to substantially the same degree. It is evident therefore that signals can be efiectively received from more distant stations than is possible without employing the invention herein described.

From the description and explanation given above, it is obvious that the invention may be employed in radio receivers for receiving radio waves of other wave length ranges. 7

Thus the invention has been applied to a radio receiver with which the same improved results have been obtained in receiving wave 7 lengths as low as 30 meters.

Should it be desired to make a radio receiver to operate over a narrower wave length range one or the other of the antenna sections may be omitted and the corresponding high frequency transformer could then be omitted without departing from the spirit of the invention.

What is claimed is 1. In a portable radio receiver, the combination of a sectional loop antenna, switching means for selecting one or more sections of said antenna and for connecting said section to the input circuit of a first three electrode tube, a second three electrode tube, and means for coupling the output circuit of the first tube to the input circuit of the second tube comprising a transformer having relatively adjustable primary and secondary ,windings, the inductance of each winding being approximately equal to the inductance of the corresponding antenna section.

2. In a radio receiver the combination of a sectional loop antenna, switching means. for selecting one or more sections of sald antenna and for connecting said sections to the input circuit of: a three-electrode electron discharge device, a second three-elec trode electron discharge devlce, means "for coupling the output circuitof the first tube to the input circuit of the second tube comprising a; plurality of transformers matched to correspond in electrical characteristics to certain sections of said antenna, andiswitching means for selectively connecting a de.

sired one of said transformers in circuit.

3. A receiver according to claim 2, where in the second mentioned switching means serves to short-circuit the transformer which is not connected in circuit.

4.- A portable radio lGCBlVGI" comprising a loop antenna, a first electron dischargeltube the same inductance as said antenna.

5. In a radio receiving set, a switching means, an amplifier tube, an antenna comprised in a plurality of spaced-apartseo tions, each connected to difi'erent contacts in said switching means, a section of said antenna being, in one position of said switch ing means, adapted to be separately connected to the input circuit of said amplifier, in which position of the switch another section of the antenna is short-circuited over said switch and said switching means in another position connecting a plurality of such antenna sections to the input circuit of said amplifier.

6. In a radio receiving set, a switching means, a plurality of sets of contacts separately engageable by said switching means, an amplifier tube, an antenna comprised in a plurality of spaced-apartsections each connected to a different one of said sets of contacts, which are interconnected so that in one position of engagement of the switching means a certain portionof said antenna is connected through said switching me'ansto said amplifier tube and another portion of said antenna is short-circuited,whereas in another position of said switching means a greater portion of said antenna is connected through said switching means to said'amplifier, whilst another portion of said antenna is short-circuited.

7. In a radio receiving set, a loop antenna having a pluralityof sections, a tube amplifier, an input circuit and an output circuit for said amplifier, means for selectively associating said sections with said input circuit,

means for selectively inserting in said output 1 I 8; In as radio receiving set, a loop-antenna: having a .plurallty of sections, a tube ampl1 I fier,.an input circuit and an output circuit for said amplifier, means for selectively associating said sections with said input circuit, means'ior selectively inserting in said out-- I put circuit a plurality oftransformer windings to correspond in wave length with the" chosen ofsaid sections, the inductance of the primary and secondary windings of any of the transformers when in operative connection being equal and being also equal'approxima-tely to the inductance of the sections which are in operative connection.

9. A radio receiver comprising'a high frequency amplifier, a detector, a plurality of; transformers, switching means for connecting" any one of said transformers in circuit to 1 couple said amplifier and said detector and for short c'ircuiting the windings of one of the transformers when another thereof is.

connected in circuit, a loop antenna connect.-

1 ed to said amplifier comprising a plurality of separate sections wound in spaced relationship and provided with taps intermediate its ends, and switchingmeans for connecting said section in series for receiving signals, said switching means also serving to shortcircuit the sections of the antenna notbeing used for receiving signals.

In testimony whereof, WILLIAM FoLwELL I-IOISINGTON has signed hisname to this specification,

' WILLIAM FOLWELL HOISINGTON. 

